Space shuttle main engine manufacturer Pratt & Whitney Rocketdyne will receive $36.9 million from NASA to continue providing shuttle main engine prelaunch and launch support through July 31.

The four-month extension, announced March 31, could be further extended if NASA’s last planned space shuttle mission, STS-135, slips much beyond its current late June launch date. Two one-month options would increase the total potential value of the contract modification to $56 million. The majority of the work, NASA said, will take place at Pratt & Whitney Rocketdyne’s Canoga Park, Calif., headquarters.

NASA has paid Pratt & Whitney Rocketdyne more than $2.2 billion since the company’s current space shuttle main engine contract began in 2002.